1. Field of the Invention
The present invention relates to a cleaning apparatus for cleaning the surface of an image carrier in an image forming apparatus of the type in which a developed image is formed on the image carrier and the formed image is used for various purposes. More particularly, the present invention relates to improvements in the above mentioned cleaning apparatus in order to minimize the possibility of the inner and outer parts of the image forming apparatus being contaminated at the time of maintenance service of the image carrier such as during removal and remounting thereof.
2. Description of the Prior Art
For a long time there has been known and widely used such type of image forming apparatus in which a developed image is formed on an image carrier, the formed developed image is used in various ways, for example, by transferring it onto a transferring member and, after the use of the image, the surface of the image carrier is cleaned up for its repetitive use.
One example of such image forming apparatus is that for the electrophotographic process in which a photosensitive medium having a photoconductive layer is used as the image carrier. The photosensitive medium is exposed image-wise to light to form an electrostatic latent image thereon and the latent image is developed on the photosensitive medium to obtain a visualized image which is then transferred for use. A concrete example of this type of apparatus is disclosed in U.S. Pat. No. 2,297,619 (Carlson), U.S. Pat. No. Re. 29,632 (Tanaka et al) or others.
Another example is that for so-called screen process in which an electrostatic latent image is formed on a photosensitive medium having a plurality of openings and an electrostatic image is formed on an insulating image carrier by modulating and controlling an ion stream in accordance with the previously formed electrostatic latent image. The electrostatic image is then developed on the image carrier to obtain a visualized image for further use. This type of image forming apparatus is disclosed, for example, in U.S. Pat. No. 3,976,484 (Ando).
Furthermore, it is known to apply to electrode pins or the like a voltage corresponding to an image signal so as to form an electrostatic image on an insulating image carrier as mentioned above and then to develop the electrostatic image.
In these image forming apparatus, the image carrier such as a photosensitive medium should be cleaned for repetitive use thereof. For this purpose, various cleaning methods have been known and used. Examples thereof include the fur brush cleaning method as disclosed in U.S. Pat. No. 3,534,427 (Severynse) and U.S. Pat. No. Re. 29,632 (Tanaka et al), the web cleaning method as disclosed in U.S. Pat. No. 3,740,864 (Ito et al) and the blade cleaning method as disclosed in U.S. Pat. No. 3,927,936 (Komori) and Re (Ito et al) U.S. Pat. No. Re. 29,632 (Tanaka et al). In particular, the last mentioned cleaning method is of high efficiency and the device required for carrying out the method is simple in structure.
For the sake of repetitive use, the image carrier used in an image forming apparatus as mentioned above is often formed as an endless member and is supported on a drum. This is known as a photosensitive drum. Since such image carrier in a form of drum must be serviced for maintenance and exchanged for a new one after a long use, it is usually constructed removably from the image forming apparatus and the mounting and removal of the image carrier is usually done independently of the associated cleaning device.
On the other hand, it is a common practice in the art that the cleaning means itself is also constructed removably from the image forming apparatus independently of other parts of the apparatus.
However, when such a photosensitive drum is removed from the image forming apparatus, there often occurs the trouble of the falling of developing powder which remains in the cleaning device or the scattering of developing powder resulting from contact of the cleaning device with the photosensitive drum. Also, developing powder which remains on the drum surface may scatter at that time. This falling and scattering of developing powder not only makes the interior of the copying machine dirty but also damages the apparatus. Developing powder scattered into gaps in the bearings or the like will disturb the smooth rotation of the shafts and reduce the durability of the apparatus. All of such troubles will finally result in a reduced reliability of the image forming apparatus.
To avoid this trouble, hitherto, it was required to remove the developing powder which remains in the cleaning device whenever the photosensitive drum was removed from the image forming apparatus. This was very troublesome and time-consuming. For the same reason, the position at which the cleaning device may be mounted was limited. This means that the cleaning device sometimes can not be mounted at the position which is considered optimum for mounting in view of the design of the copying machine.
All of the above problems are solved by the present invention.